Hastospiculum nordestinum, Ferreira-Silva & Alcantara & Ávila & Silva, 2020

Ferreira-Silva, Cristiana, Alcantara, Edna P., Ávila, Robson W. & Silva, Reinaldo J., 2020, A new species of Hastospiculum Skrjabin (Spirurida: Diplotriaenidae) parasite of Xenodon merremii (Walger in Spix) (Serpentes: Dipsadidae) from Northeastern Brazil, Zootaxa 4878 (2), pp. 362-374 : 364-369

Hastospiculum nordestinum n. sp.

( Figs. 1–3 )

urn:lsid:zoobank.org:act:DECDAB88-12A8-4C98-B1CE-B9B759A1C354

Description (based on 4 adult males, and 5 adult females). White coloration in vivo, body long, cylindrical, wider in anterior end, slightly tapering at posterior end. Cuticle striated transversely provided with protruding quitinized thickening, irregular in shape and arrangement ( Fig. 1H ). Mouth elongated, dorsoventrally directed, with two small quitinized tooth-like projections laterally situated ( Fig. 1A, B , 3C ). Small oral cavity. Four large cephalic papillae: one laterodorsal and one lateroventral pairs. One pair of amphids lateral to tooth-like projections ( Fig. 1A, B , 3C ). Esophagus distinctly divided into two sections: a short anterior muscular section, and a long thick glandular portion ( Fig. 3A ). Nerve ring transverse to muscular esophagus ( Fig. 3A ).

Male (based on the holotype, and 3 paratypes). Body 17.3–35.1 mm (18.1 mm) length by 385.7–726.5 (385.7) width; body width at nerve ring level 316.3–481.1 (316.3); at alae region 136.8–181.9 (171.1). Muscular esophagus length 147.2–294.4 (165.7); Glandular esophagus length 4.0– 4.6 mm (4.0 mm); body width 355.7–583.1 (365.1) at glandular esophagus-intestine junction level. Nerve ring 119.1–149.3 (130.8) from anterior end. Caudal end with pre- and postcloacal papillae; caudal lateral alae not surrounding the tail end, unconnected ( Fig. 2A, B ). Cloaca 83.9–133.3 (90.4) from posterior end. Eight pairs of pedunculated caudal papillae [three precloacal, one paracloacal, and four postcloacal pairs (1 larger and 3 small pairs at terminal end)]. Two phasmids on each side of the tail apex ( Fig. 1G , 2A ). Three adcloacal sessile papillae: one anterior unpaired and two lateral ( Fig. 1E, G , 2A, B ). Two unequal spicules; left substantially longer than right; [719.6–902.4 (719.6) and 247.4–272.9 (272.9), respectively]. Gubernaculum absent ( Fig. 2C ).

Female (based on the allotype, and 4 paratypes). Body 23.8–62.4 mm (62.4 mm) length by 450.6–712.5 (698.4) width; body width 302.8–514.2 (514.2) at nerve ring level. Muscular esophagus length 221.2–283.3 (221.2). Glandular esophagus length 4.1–7.2 mm (4.4 mm); body width 396.4–702.5 (569.6) at glandular esophagus-intestine junction level. Nerve ring 113.7–145.4 (125.7) from anterior end. Didelphic, opisthodelphic, vulva without protruding lips ( Fig. 1D , 3A ), 168.3–506.7 (382.9) from anterior end ( Fig. 1C , 3A ). Vagina 796.7–1617.2 (1617.2) long, by 134.2–244.5 (225.2) wide, strongly muscular, with glandular portion at anterior extreme 478.4–638.5 (638.5) ( Fig. 1D , 3A ). Posterior end slightly conical, anus subterminal ( Fig. 3B ), located 34.2–84.1 (65.1) from posterior end. Embryonated eggs, spherical, with two layers, the inner thin and dense and the external thick and hyaline, 53.4–55.9 long, 46.5–48.9 wide ( Fig. 1F , 3D ).

Diagnosis. Hastospiculum nordestinum n. sp. is characterized by possessing two pairs of large cephalic papillae, caudal end ornamented with lateral alae, not surrounding the tail end and unconnected, supported by eight pedunculate pairs of papillae: three precloacal, one paracloacal, and four postcloacal (first pair large and the other three small on tail end) and three sessile papillae adcloacal; left spicule length 719.6–902.4 µm; and a cuticle striated transversely provided with protruding quitinized thickening.

Taxonomic summary.

Type host: Xenodon merremii (Wagler in Spix) (Serpentes: Dipsadidae ).

Type locality: Municipality of Barbalha (7º16’59.0” S, 39º18’37.4” W), Ceará State, Northeastern Brazil .

Site of infection: Body cavity.

Intensity of infection: 10

Voucher specimens: Holotype male ( CHIOC 38964 a); allotype female ( CHIOC 38964 b); paratypes ( CHIOC CHIOC 38964 c–d). Other vouchers ( CHIBB 9122–9124 ).

Etymology. The epithet of the new species refers to the Northeastern region of Brazil where the snake host was collected.

Remarks. Regarding the left spicule length, Hastospiculum nordestinum n. sp. most closely resembles H. bipinnatum (1.01 mm), H. cubaense (0.86 mm), H. digiticaudum (0.97–1.13 mm), H. gouldi (1.1 mm), H. uncertenum (1.2 mm), and H. venezuelense (1.3 mm). In other Hastospiculum species, the left spicule is 2 to 4 times longer than in Hastospiculum nordestinum n. sp. ( Table 2 ). Among these similar species, only H. digiticaudum has male caudal alae not surrounding the tail end and are not connected, as recorded in Hastospiculum nordestinum n. sp. However, H. digiticaudum differs from Hastospiculum nordestinum n. sp. in the arrangement and number of caudal papillae, since it presents only five pairs of pedunculated papillae, three precloacal, one pair paracloacal, and one postcloacal (vs. eight pairs of pedunculated caudal papillae present in Hastospiculum nordestinum n. sp.). Therefore, our species is unique, justifying the description of a new species for the genus Hastospiculum .

Among the species of Hastospiculum recorded in Brazil, only H. onchocercum has been recorded in the state of Pernambuco, Northeastern Brazil. This species differs from Hastospiculum nordestinum n. sp. by the following characteristics: the presence of four pairs of cephalic papillae (vs. two pairs in the new species), caudal alae surrounding the tail end (vs. free tail in Hastospiculum nordestinum n. sp.), one pair of conical processes at the end of the tail (vs. absent in the new species described herein), and by the left spicule length (1.84–2.2 mm vs. 0.7–0.9 mm, respectively).

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Figures

FIGURE 1. Hastospiculum nordestinum n. sp. A. anterior view of female head en face (arrows indicate cephalic papillae); B. lateral view of male head (arrow indicates amphid); C. anterior end of female, lateral view; D. Vagina; E. tail of male, ventral view; F. Egg; G. caudal papillae of male, ventral view (arrows indicate phasmids); H. cuticle, showing protruding chitinized thickening. Scale bars: 50 µm (A, B, F, G), 200 µm (C, H), 100 µm (D, E).

FIGURE 2. Male of Hastospiculum nordestinum n. sp. A. tail, showing spicule and caudal papillae, ventral view; B. tail, lateral view; C. spicules. The left spicule was sectioned to represent both extremities and to fit in the plate. Scale bars: 200 µm (A), 50 µm (B), 100 µm (C).

FIGURE 3. Female of Hastospiculum nordestinum n. sp. A. anterior end, lateral view; B. tail, lateral view; C. anterior view of head en face; D. embryonated egg. Scale bars: 200 µm (A), 100 µm (B), 50 µm (C, D).